Common (Translated Scientific) Name: Engelmann Spruce / Twinflower Forest

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This forest association has been described from western and south-central Montana and northwestern Wyoming. Sites supporting stands of this association are in the habitat type of the same name, and include steep slopes, gentle northeastern slopes, alluvial terraces, and well-drained benches that shed cold air, in an altitude range of 1890-2500 m (6200-8200 feet). The soils are generally non-calcareous. The vegetation consists of a tree overstory dominated or codominated by Picea engelmannii and often containing the seral species Pinus contorta and Pseudotsuga menziesii. Picea engelmannii and/or the Picea x albertiana hybrid are the diagnostic tree species in this forest association. The shrub layer often is dominated by Vaccinium membranaceum, Vaccinium scoparium, Alnus viridis ssp. sinuata, or Symphoricarpos albus. Juniperus communis (typical of dry sites) may also be a common species in southern stands. Linnaea borealis contributes at least 5% of the undergrowth cover and often dominates or codominates the undergrowth. Other common species are Calamagrostis rubescens (which may dominate the undergrowth), Arnica cordifolia, Chamerion angustifolium, Fragaria vesca, Osmorhiza berteroi, and Orthilia secunda.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This association is based on the descriptions of the Picea engelmannii / Linnaea borealis habitat type in Wyoming and the Picea / Linnaea borealis habitat type in Montana. Following the convention used for Rocky Mountain subalpine forests, this association includes stands with very little or no Abies lasiocarpa; that species clearly is not a codominant. Stands in which the tree component is a mix of Abies lasiocarpa and Picea engelmannii are considered part of the closely related ~Abies lasiocarpa - Picea engelmannii / Linnaea borealis Forest (CEGL000315)$$. This distinction is more easily made for the stands in Wyoming than in Montana. This type was first described as the Picea / Linnaea borealis habitat type by Pfister et al. (1977) for Montana. Therefore, we have adopted Picea spp. as diagnostic, regardless of overstory dominance. The authors mention in their classification of the Picea habitat types that a strong relationship between hybridization and habitat type or geographical area was not indicated, and chose to group the hybrid and pure Picea engelmannii together under the Picea name. Following this same logic, former Picea (engelmannii x glauca, engelmannii) / Linnaea borealis Forest (CEGL000411) recorded from Montana has been merged with the former pure Picea engelmannii / Linnaea borealis Forest (CEGL000370) into this single association, which could include stands with either pure Picea engelmannii and/or Picea x albertiana (= Picea engelmannii x glauca) hybrid. The amount of Linnaea borealis that must be present, relative to other undergrowth plants, to place a stand into this association apparently has not been clearly stated.

Similar NVC Types: No Data Available

note: No Data Available